6600 vs 6700 receiver performance differences - flex dinner 2017

At the Flex dinner on Saturday night Steve mentioned that the 6600 receiver performance would be better than the 6700. I have several questions related to this. This performance difference is in addition to the bandpass filter enhancement in the 6600.

1 -@Steve, can you describe / explain the details on the receiver improvement difference, I didn't see this performance difference mentioned in the spec sheets. Are there hardware differences responsible?

2 - @Gerald, in an earlier post about the Sherwood receiver differences when he was restesting a radio his results varied although there were no hardware or software differences in the radio under test. You mentioned finding some new settings that would improve the performance. And indicated that they would be incorporated in a future ssdr release. Is this still planned? Will they be coming out in 1.x or 2.x?

Looks like there are lots of questions about Hebrew radios, which I also have.

I would suggest that Flex creates a comparison table with all the products listed, including the ones that have been replaced recently (6300 and 6500). That may not answer all the details but would highlight the major points. This would help customers and minimize the amount of questions and postings in the forum, which will become hard to refer to later for making a decision.

Hi Eduardo,
There is a model comparison sheet available that addresses the highlights but it does not provide the details and the receiver performance differences specifically between the 6600 and 6700.

I would like to know what they are, and how they are achieved (hardware, and or software).

This level of detail would not likely be something that could be explainred in a chart.

I did click on the Compare Tab but no joy. What I was looking for is a comparison of 6300 to 6400 and 6500 to 6600 so I can decide if the difference is worth the cost to upgrade to a 6400 or a 6600. I have a 6300 and if the biggest difference between 6300 and 6400 is the software, I might keep my 6300 and buy V2.

Ken,The latest comparison table only shows the new models and 6700 (since it is still in the lineup) as you noted. I doubt they will publish anything new that includes the 6300 or 6500. Here is a snapshot with both the new and old model comparison tables side by side that may help some.

Eventually when either Rob Sherwood or the ARRL tests the new models for receiver performance there will be some additional data available. That could be a long wait though.

Since the 6700 remains at the top of the line (at least by the numbers) that is why I want to get the details on any real or perceived differences in the receiver performance. I did see some video that suggests the enhancement that Gerald referred to in #2 above is planned.

I am going to answer several questions on the topic and then go QRT on the subject for now. Here are the facts in bullet form, which is how I think:

This was not a software bug. The software related to this setting has been the same since we released each radio model. This is not in code that the software team would normally touch.

I would call this a "discovery" because I serendipitously found a setting that increased SFDR headroom that was counter intuitive to what I thought I knew about the hardware.

I made all the adjustments manually so they are not yet in the software. When we do update the software, it will be in the release notes.

Further testing is needed on the 6500/6700 to see if the same settings apply. A very quick look indicates that it will apply.

This is not something that alpha testers can be expected to test. It would even be complex and expensive to do at the factory.

I agree that independent testing should provide the version number of the software/firmware. The ARRL does this.

@Rick. This topic has been covered many times over the years but I am sure you missed it. This is a common minsconception. First, never trust a superhet S meter. They are not accurately calibrated at 6 dB per S unit. They reduce that so that you are fooled into thinking the noise is lower that it actually is. On 40m the atmospheric noise on your antenna is actually going to be in the range of S3 to S4 in 500 Hz bandwidth - more in a SSB bandwidth. See the chart below. Also, when you use the 0 dB gain setting on our radios, that means literally 0 dB gain. There is no analog gain stage in that setting, which is the most appropriate way to run a radio below 15m and sometimes even on 15m. Add gain to lower the noise floor on 15m and above. That's why the control is there.

@The main original question - FRS was clear the new hardware had NOT been formally "tested" rather both the design expectations and their initial hands-on with the new hardware indicates the new 6600 receiver to have an edge over the 6700.

When I asked was that edge likely to be enough to discernible by the operator, or was it something only test instruments would notice, there wasn't a clear answer.

The internalized better filtering on contest bands (ONLY) in the 6600 will have an advantage for some operations, but even that may have little noticeable benefit for the average operator.

The testing tweaks Sergey points out may or may not also apply to the 6600 hardware.

Yeah Steve, i know this offer, from my point of view this is a good solution for 6300 (which have no BPF) or remote reciever but not sure that is applicable for 6700 - i have doubts with IP3 of this filters what can decrease overall dinamic range of 6700. I think for Top Gun`s users(owners :-) ) are should to look into BPF capable with 100w TX, for instance:

Question Number One1 -@Steve, can you describe / explain the details on the receiver improvement difference, I didn't see this performance difference mentioned in the spec sheets. Are there hardware differences responsible?

Below is question #1 about the receiver improvement over the 6700 but rephrased and with more detail.

When I heard there was improved hardware I wondered if the 6600 had a different FPGA ( i.e. is this the improved hardware?). But maybe there are some other changes. My assumption is that a new FPGA would also have different software/firmware. That combination would allow for improved processing.

We often hear that the SSDR software is the same across all models but there are nuances to that statement:

There will still be differences in the server side software that executes which are "under the hood." The server side software executing will be different based on the radio capabilities ( number of SCUs, preamp capabilities, ATU, etc).

If the hardware is substantially different (e.g. a different FPGA, other CPU/processor, I/O components, etc) the software executing may also be significantly different.

Although the client side software for a given platform looks basically the same for everyone, even there it has to be flexible and know the capabilities of the radio it is connected to. For example, how many slices to display, preamp capabilities, etc. So some branches of the code will / will not execute for all depending on those differences.

A given "release" will work on all the radios and SSDR for the client will support them all. But the actual code executing on your radio and client application will depend on the server capabilities.

And obviously the the client software that is executing also depends on OS environment (PC, Maestro, iPad, etc).

Back to the basic question:

Are FPGA and firmware the same for the 6600 and 6700?

If not, what changes make up the improved hardware?

What other changes are responsible for the performance improvement of the 6600 over the 6700?

Tim,Thanks for the feedback and I can understand not wanting to disclose the hardware details at this time. I guess once the radios are in the hands of the users or even the competitors ;-) someone will pop the hood and figure out what the major changes are. But no need to make it easy for them now. I'd like to know but can wait...

I'm also glad to hear you confirm that the firmware is different for every radio ( i.e. the Hardware Abstraction layer). I don't think some realize this when they hear that the SSDR software is the same across all models. That is why there can be different features (and bugs) in one model and not another.

On RMDR - reciprocal mixing dynamic range. Will FRS will publish some data on this when the production models are released? Eventually I guess the ARRL or Rob Sherwood will test and publish their findings.